The present invention relates to a ring bus arrangement type gas insulated switchgear.
In a conventional ring bus arrangement type gas insulated switchgear, a plurality of circuit breaker units and a plurality of line side units are oppositely arranged and connection bus units are arranged between the circuit breaker units and the line side units, oppositely arranged, as disclosed in JP A 57-211915, JP A 59-6706, JP A 3-245706 or JU A 5-33610. However, in such a construction, the connection bus is very long because the connection bus is stretched around in horizontal and vertical directions.
Further, there are a ring bus arrangement type gas insulated switchgear in which a plurality of circuit breaker units and a plurality of line side units are alternately arranged in loop as a ring bus arrangement type gas insulated switchgear disclosed in JP A 58-75413 or JP A 9-261810, and a ring bus arrangement type gas insulated switchgear in which connection bus units each are formed in loop and a plurality of units each of which formed by connecting a circuit breaker unit and a line side unit are arranged along the connection bus units as a ring bus arrangement type gas insulated switchgear disclosed in JP A 48-42338, JP A 10-108327 or JP A 2-254908. However, in such a construction, an installation area increases according to increase in the number of circuit lines and it becomes necessary to disassemble and move each unit in the case where circuit lines are added.
Still further, there is a ring bus arrangement type gas insulated switchgear in which a plurality of circuit breakers each phase-separated and horizontally laid are arranged and axial ends of the plurality of circuit units are alternately connected in series for each phase by connecting bus units, as a ring bus arrangement type gas insulated switchgear disclosed in JP A 54-109835. However, in such a construction, the length of the circuit breaker units in an arrangement direction becomes long and an installation area increase because phases are separated. Further, on the contrary, when the circuit breaker is constructed so as to be laid horizontally in lump of three phases, branches from the circuit units become complicated and it is necessary to stretch around the connection buses in an up and down direction.
An object of the present invention is to provide a ring bus arrangement type gas insulated switchgear which is able to reduce its cost by shortening the length of a connection bus. In addition, another object of the present invention is to provide a ring bus arrangement type gas insulated switchgear which is able to reduce an installation area, to simplify addition of circuit lines, or to improve the workability of maintenance and inspection.
A basic feature of the present invention is to arrange a plurality of T-branched circuit breaker units in a direction perpendicular to their branch directions and connect adjacent circuit breaker units by connection bus units alternately left and right of the arrangement direction of the circuit breaker units on a horizontal plane of approximately the same height as the T-branch portions of the circuit breaker units, that is, to connect them in a rectangular wave shape. By such connection, the connection bus are stretched around on the horizontal plane of approximately the same height as the T-branch portions of the circuit breaker units and not stretched around in an up and down direction, whereby it is possible to reduce the length of the connection bus by an amount corresponding thereto. Therefore, it is possible to reduce the cost. Further, by arranging a return bus unit below the connection bus unit, it is possible to shorten the length of buses connecting the return bus unit and the connection buses, so that the cost can be reduced further.
Further, according to the connection as mentioned above, it is possible to easily carry out an extension by taking off a connection portion of the connection bus unit and the return bus unit, increasing a unit of one circuit line, that is, a unitary unit composed of a circuit breaker unit, current transformer unit, connection bus unit and line side unit, and a return bus unit, and connecting again the taken off connection portion of the connection bus unit and the return bus unit. Further, the taken off parts can be used again, so that a new unit product is not accompanied.
In the present invention, the connection bus unit, the current transformer units and the line side units are connected on the horizontal plane of approximately the same height as the T-branch portion of the circuit beaker units, so that a space below them can be effectively used. In the present invention, a control box is arranged in the space, so that an installation area can be reduced by an amount corresponding thereto. Further, a space reverse to the space in which the control box is disposed can be used as a space for maintenance inspection of an operation device of the circuit breaker, so that it is possible to easily effect the maintenance inspection.
In the present invention, current transformers are not incorporated in the circuit breaker unit 12, but they are provided separately as the current transformer units 13. By providing the current transformers separately in this manner, the current transformers can effect precise current detection without affection of current interruption arcs of the circuit breaker, and it is possible to improve the reliability. Further, by providing the current transformers separately, even if an accident occurs on the opposite-to-circuit-breaker side of the current transformer, a power supply failure region can be limited to only the corresponding accident circuit line without interruption of circuits of all the circuit lines. Therefore, it is possible to improve power supply service.
In the present invention, a circuit construction by a single connection line and a real apparatus construction are constructed the same as each other, that is, along skeletons of the units. By taking such a construction, even if an accident occurred, the accident portion can be easily found, so that it is possible to restore the portion of the accident soon. Therefore, the reliability can be increased. Further, in the case of maintenance inspection, since inspection portions can be easily found, it is possible to increase the workability of the maintenance inspection. Further, the circuit construction by a single connection line is applied on an operation panel of a monitoring room as a simulation bus, and operation switches of each apparatus are mounted on the simulation bus. If the circuit construction by a single connection line and the real apparatus construction are the same as each other, it is possible to prevent erroneous operation by operators.